The influence of mineral and carbon sources on biological control of charcoal rot fungus,Macrophomina phaseolinaby fluorescent pseudomonads in tomato

Nine spots on a meat mincer in a large catering facility were sampled four times over a three-month period after routine cleaning and disinfection. Spot 2 carried a significantly higher average microbial load than the other spots and was the only spot with a persistent population of fluorescent pseudomonads. The predominant type of fluorescent pseudomonads produced a yellow diffusible pigment and were always found in turkey meat. Since turkey was also the last type of meat minced on each working day, it was considered the likely source of these bacteria on the mincer. Sixty-three yellow-fluorescing pseudomonad strains from un-minced turkey and 17 strains from mincer spot 2 after mincing, cleaning, and disinfection were subjected to fingerprint analysis by random amplification of polymorphic DNA (RAPD) and by analysis of the assimilation patterns of 95 carbon sources using the Biolog system. Cluster analysis of the RAPD and the metabolic fingerprints revealed that all the mincer strains formed a homogeneous cluster, exclusive of all the turkey strains which displayed a higher degree of heterogeneity. Six strains isolated 1 week earlier and six strains isolated 11 weeks earlier from spot 2 were also subjected to RAPD analysis. Their fingerprints fell within the existing cluster of 17 spot 2 strains. These results suggest the existence on mincer spot 2 of an endemic flora of fluorescent pseudomonads, probably in the form of a biofilm. The genetic and physiological homogeneity of this flora, as opposed to the heterogeneity of the raw meat flora, indicates that only a fraction of the raw meat population of P. fiuorescens is successful in forming biofilm in this environment.

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Assessment of the Importance of Similarity in Carbon Source Utilization Profiles between the Biological Control Agent and the Pathogen in Biological Control of Bacterial Speck of Tomato

Applied and Environmental Microbiology ◽

10.1128/aem.68.9.4383-4389.2002 ◽

2002 ◽

Vol 68 (9) ◽

pp. 4383-4389 ◽

Cited By ~ 42

Author(s):

Pingsheng Ji ◽

Mark Wilson

Keyword(s):

Biological Control ◽

Carbon Source ◽

Disease Severity ◽

Pseudomonas Syringae ◽

Biological Control Agent ◽

Carbon Sources ◽

Control Agent ◽

Carbon Source Utilization ◽

Bacterial Speck

ABSTRACT Bacterial speck of tomato, caused by Pseudomonas syringae pv. tomato, was used to determine whether similarity in carbon source utilization between a preemptive biological control agent and the pathogen was significant in determining the ability of the bacterium to suppress disease. Similarity in carbon source utilization was quantified as the ratio of the number of tomato carbon sources utilized in vitro by the biological control agent to the number of tomato carbon sources utilized in vitro by the target pathogen (the niche overlap index [NOI]). Suppression of the disease was quantified as the percent reduction in disease severity compared to the pathogen-only control when nonpathogenic bacteria were applied to foliage 48 h prior to the pathogen. In the collection of 36 nonpathogenic bacterial strains, there was a significant (P < 0.01), but weak (r2 = 0.25), correlation between reduction in disease severity and similarity in carbon source utilization, suggesting that similarity in carbon source use was significant in determining ability to suppress disease. The relationship was investigated further using catabolic mutants of P. syringae strain TLP2, an effective biological control agent of speck. Catabolic mutants exhibited lower levels of similarity (NOI = 0.07 to 0.90) than did wild-type TLP2 (NOI = 0.93). With these catabolic mutants there was a significant (P < 0.01), and stronger (r2 = 0.42), correlation between reduction in disease severity and similarity in carbon source utilization. This suggests that similarity in carbon source utilization was a more important component of biological control ability for the catabolic mutants than for the nonpathogenic bacteria. Together, these studies indicate that suppression of bacterial speck of tomato was correlated with nutritional similarity between the pathogenic and nonpathogenic bacteria and suggest that preemptive utilization of carbon sources was probably involved in the biological control of the disease by both the naturally occurring nonpathogenic bacteria and the catabolic mutants.

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Biocontrol of charcoal rot in sorghum by fluorescent pseudomonads associated with the rhizosphere

Crop Protection ◽

10.1016/j.cropro.2008.07.001 ◽

2008 ◽

Vol 27 (11) ◽

pp. 1407-1414 ◽

Cited By ~ 28

Author(s):

I.K. Das ◽

S. Indira ◽

A. Annapurna ◽

Prabhakar ◽

N. Seetharama

Keyword(s):

Fluorescent Pseudomonads ◽

Charcoal Rot

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Biological control of soil-borne pathogens by fluorescent pseudomonads

Nature Reviews Microbiology ◽

10.1038/nrmicro1129 ◽

2005 ◽

Vol 3 (4) ◽

pp. 307-319 ◽

Cited By ~ 1345

Author(s):

Dieter Haas ◽

Geneviève Défago

Keyword(s):

Biological Control ◽

Fluorescent Pseudomonads ◽

Soil Borne Pathogens

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Lobesia botrana: A Biological Control Approach with a Biopesticide Based on Entomopathogenic Fungi in the Winter Season in Chile

Insects ◽

10.3390/insects13010008 ◽

2021 ◽

Vol 13 (1) ◽

pp. 8

Author(s):

Fabiola Altimira ◽

Nathalia De La Barra ◽

Paulo Godoy ◽

Juan Roa ◽

Sebastián Godoy ◽

...

Keyword(s):

Biological Control ◽

Entomopathogenic Fungi ◽

Carbon Sources ◽

Winter Season ◽

Pupal Stage ◽

Lobesia Botrana ◽

Moth Population ◽

Metarhizium Robertsii ◽

Control Approach ◽

Table Grapes

Lobesia botrana (Denis and Shiffermüller) (Lepidoptera: Tortricidae) is one of the main pests that affect the production and export of table grapes in Chile. Because this pest has quarantine status, the fruit must be fumigated with methyl bromide, which reduces the fruit’s export competitiveness in the destination market. In the present study, to help resolve this issue, six native entomopathogenic fungi were identified through multilocus analysis, including three Beauveria pseudobassiana and three Metarhizium robertsii. These fungi were evaluated in the laboratory to control L. botrana in its pupal stage in a silk cocoon and compared against a biological control product. Formulations with additional carbon sources improved the performance of the fungi. The treatments with outstanding performance contained the fungal strains B. pseudobassiana RGM 2184 and M. robertsii RGM 678. These strains were evaluated in the field during the winter season in two different regions of the country; the strains reached maximum efficacies of 80% and 88%, respectively, at 21 days post first application. Therefore, entomopathogenic fungi can contribute to reducing pupal populations in winter, thereby decreasing the moth population in spring–summer.

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